Plugin development has became so advanced, you can now have any emulation of any compressor, for a fraction of the cost. But do you know the different styles of compression, and when you might want to use one over another? Let's find out more!
The five main types of compressor groups:
- Optical (Opto)
- Valve (Tube)
Fet (field effect transitor)
FET stands for 'field effect transistor' and is notably the most famous type of compression that you probably already own in plugin format. Yes, I'm talking about the world famous 1176. The 1176 is renown for its punchy characteristics and ultra fast attack and release controls. For this reason mixers love to utilise the 1176 on vocals, as it catches transients super fast while retraining dynamic range. It's also used in more heavy handed scenarios such as parallel compression on drum room mics. The famous 'all buttons in' ratio is one of the best ways to make any room sound absolutely enormous!
Optical compressors (or opto) are dependant on light sensitive resistors. The audio signal feeds a light element (such as an LED), which then shines onto a light-sensitive resistor. The resistance of this element then informs the compression circuit how much and how quickly to attenuate the incoming audio signal. This results in a compression style that is often described as natural and smooth. Optical compressors have a much slower attack and release time to FET compressors. For this reason engineers love to use them on lead lines, vocals, bass and anything that needs overall levelling. A famous example of an opto compressor is the Teletronix LA-2A.
Valve / tube compressors
Valve (or tube) compressors use a tube stage to control the gain reduction. This characteristically imparts a warm smoothness and slight harmonic distortion to the sound. Tube compression will change the tone of an audio signal the most due to its colouring nature. For this reason the Fair Child 670 is one of the most sought after and expensive compressors of all time. They're mostly used after tracking to add warmth to drums, vocals, basses and even in mastering.
VCA compression runs on a voltage controlled amplifier. They're often cheaper than opto or tube compressors and they don't colour the signal as much. They're widely used on the mix bus due to their transparency and superior gain reduction. If pushed hard they can also create some harmonic distortion and pumping. The SSL G comp is the most famous example of a VCA compressor. Used for its easy functionality and program dependant auto release control.
Digital might seem like a dirty word, but many mix engineers would be lost without some form of digital compression. The most notable advance in modern compression was the introduction of the multi band compressor. This allowed mixing engineers to control specific frequencies of an audio signal, and then determine its threshold, bandwidth and ratio accordingly. The Fab Filter Pro-MB is a great example of a powerful and intuitive multi band compressor.
Below are a few of my go to plugins for all of the above compression types.
- UAD 1176
- UAD Teletronix LA-2A
- Arturia STA Level
- Klanghelm MJUC (also for delta MU style compression)
- UAD Fairchild 670
- Waves SSL G Comp
- Fab Filter - Pro MB